A waterbombing pilot fighting a NSW blaze was killed after his plane’s wing broke off mid-flight as a result of cracking and corrosion that was missed during an “inadequate” inspection months earlier, an inquest has found.

David Black, 43, died when his M18 Dromader aircraft crashed in an isolated and mountainous area of the Budawang National Park, in the state’s south, on October 24, 2013.

The experienced pilot was preparing to attack a bushfire when the left wing of his aircraft suddenly broke off, causing the aircraft’s rapid descent, Deputy State Coroner Derek Lee wrote in his inquest findings released on Monday.

Mr Black left behind his wife of 12 years, Julie, and three young children.

“David and Julie had worked together as a team, industriously, to reach a stage in life where their business was successful, their family was nurtured and cared for, and they were simply able to enjoy life,” Mr Lee wrote.

“To lose David in sudden circumstances is heart-rending.”

The plane Mr Black was flying was owned by his company, Rebel Ag, which provided aerial support to the NSW Rural Fire Service.

It was tested and inspected just over two months earlier by two companies, Aviation NDT and Beal Aircraft Maintenance, but Mr Lee said the work was inadequately done.

He wrote in his findings that testing by Aviation NDT used an unauthorised method and did not comply with the mandatory requirements of the Civil Aviation Safety Authority.

Further, the plane’s wings were not removed during a visual inspection by Beal Aircraft Maintenance, meaning that corrosion and cracking on one of the left wing’s attachment lugs was not detected.

By the time Mr Black crashed in October, the Australian Transport Safety Bureau found that cracking on the inner surface of the lug had reached a critical length of 10.4 millimetres and at least 32 secondary micro cracks were also identified.

The engineer behind the visual inspection, Donald Beal, told the inquest the manufacturer’s service bulletin did not mandate removal of the wings, so he didn’t see any need to remove them.

Mr Beal also said there was ambiguity about what visual inspections actually involved, Mr Lee recalled in his findings.

At the NSW Coroner’s Court on Monday, Mr Lee recommended that CASA consider issuing a directive that wings be removed during inspections of M18 Dromader planes.

He also recommended they consider a different way of calculating fatigue damage, which did not just rely on flight hours but also looked at other factors that age an aircraft, such as its speed and the weight of loads that it carries.

A CASA spokesman said they would consider the recommendations carefully.